The present invention relates to an ophthalmic characteristic measuring apparatus, and particularly to an ophthalmic characteristic measuring apparatus in which before the optical characteristics of a subject eye, the corneal shape of the subject eye and the like are calculated, data suitable for the calculation can be more accurately selected by visual confirmation.
In recent years, optical instruments used for medicine have had extremely various applications. Particularly, in ophthalmology, the optical equipment has come into wide use as an optical characteristic measuring apparatus for examining ophthalmic functions such as refraction of an eye or adjustment thereof and the inside of an eyeball. In the measurement results of various examinations, it is important that the patient""s eye to be measured as the object of examination is put in what kind of decision factor for measuring timing.
In general, cornea topography is effective for many uses, for example, an estimate of result of an operation such as keratotomy or keratectomy, clinical test after corneal transplant, design and evaluation of a contact lens for myopia/hyperopia, and diagnosis/disease judgment of a cornea. As a conventional method of measuring the corneal shape, there is, for example, a placido disk technique, a stereogram technique, a moire technique, a topography interferometric technique or the like.
As the optical characteristic measuring apparatus, for example, there is known an apparatus in which light of a point light source is projected onto an eye-ground, is converted into a predetermined number of beams by a converting member such as a Hartmann plate, and the beams are received by a light receiving section to measure the optical characteristics of the eye, or a corneal shape measuring apparatus for measuring the corneal shape by using placido""s disc with visible light. Incidentally, in the present specification, a signal obtained through the Hartmann plate and needed to measure the optical characteristics of the eye to be measured is made a first signal, and a signal obtained through the placido""s disc and needed to measure the corneal shape of the eye to be measured is made a second signal.
When the ophthalmic characteristics are calculated, the measured first signal and second signal are not necessarily suitable.
Besides, in general, at the point of time when alignment is adjusted manually or automatically, a measurement is manually or automatically started. A coordinate system (CCD coordinate) incident to a CCD at the time of the measurement corresponds to a CCD coordinate at the side of an opposite object (eye side) through the CCD and lens. Although a Hartmann wavefront sensor measurement (first measurement system) and a corneal shape measurement (second measurement system) are made almost simultaneously in the respective CCDs, there is a case where the measurements are not made strictly at the same time. Thus, in the measurements, a main cause is, for example, movement of the eye, and it is not assured that the CCD coordinate system of the first measurement system becomes equal to the CCD coordinate of the second measurement system. It has been already carried out that the edge of a pupil is obtained from an anterior eye image and is used for the alignment. However, in the case where the acquisition timing of the Hartmann image is not completely coincident with the acquisition timing of the anterior eye alignment image, if the alignment is made by only the anterior eye alignment image, there is a possibility that a deviation occurs in the alignment of the Hartmann measurement by ocular movement, etc. As stated above, it is supposed that it is difficult for the conventional optical characteristic measuring apparatus to simultaneously measure the optical characteristics of the eye to be measured and its corneal shape.
In view of the above, an object of the present invention is to provide an ophthalmic characteristic measuring apparatus including wavefront measurement in which data processing is effectively carried out. Particularly, the invention has an object to enable selection of data suitable for calculation by visual confirmation before the calculation of optical characteristics of the subject eye and the corneal shape of the subject eye.
Besides, another object of the invention is to provide a structure suitable for capturing a first signal of a first measurement system and a second signal of a second measurement system simultaneously or substantially simultaneously.
Besides, still another object of the invention is to provide a structure suitable for continuously capturing the first signal and the second signal simultaneously or substantially simultaneously.
Besides, still another object of the invention is to make a measurement at the time when the first signal and the second signal come to have states suitable for the measurement.
Besides, still another object of the invention is to make a measurement such that when there are a plurality of factors to influence the measurement, the suitableness of those factors is judged with signals which can respectively detect them with ease, and the measurement timing is determined, so that the measurement is made in the state where a highly reliable measurement result can be obtained.
According to the invention, an ophthalmic characteristic measuring apparatus comprises:
a first light source for emitting a first light flux of a first wavelength of near infrared;
a first illumination optical system for illuminating a minute region on a retina of a subject eye with the light flux from the first light source;
a first light receiving optical system for receiving a part of a first reflected light flux of the first light flux from the first light source, reflected from the retina of the subject eye, through a first conversion member for converting it into at least 17 beams;
a first light receiving section for receiving a first received light flux guided by the first light receiving optical system to form a first signal;
a second light source section for emitting a second light flux of near infrared having a second wavelength longer than the first wavelength of the first light flux;
a second illumination optical system for illuminating a vicinity of the cornea of the subject eye with the second light flux from the second light source and with a predetermined pattern;
a second light receiving optical system for receiving a second reflected light flux of the second light flux from the second light source, reflected from the vicinity of the cornea of the subject eye;
a second light receiving section for receiving a second received light flux guided by the second light receiving optical system to form a second signal;
a display section for displaying, as an image, the first and/or the second signal from the first light receiving section and/or the second light receiving section;
an input section for selecting the first and/or the second signal used for a calculation processing on the basis of an image display of the first and/or the second signal displayed on the display section; and
a calculation section for obtaining optical characteristics of the subject eye and a corneal shape of the subject eye on the basis of first and second signals corresponding to the first and/or the second signal selected by the input section.
One of the features of the invention is that, for example, the optical characteristics of the subject eye (for example, refractivity) is measured on the basis of the first signal from the first light receiving section (or a tilt of the light flux obtained by the first light receiving section), and the corneal shape is measured on the basis of the second signal from the second light receiving section. Another feature of the invention is that for example, the first signal and the second signal can be captured simultaneously or simultaneously and continuously several times without miosis of the subject eye. Another feature of the invention is that for example, the timing of capturing the first signal and the second signal suitable for the measurement can be determined. Another feature of the invention is that for example, separate factors are judged with the first signal and the second signal, or plural factors are judged only with the first signal or the second signal, whereas important factors (for example, blink) can be judged using both the first signal and the second signal.